This invention relates to a track access method of a disc for accessing a track of an objective or destination block at high speed in an optical disc or a magneto-optical disc.
Present track accessing methods of discs generally calculate the number of tracks from the present block to the objective block and perform track jumping by a tracking means to the calculated number of tracks.
However, in such conventional track accessing methods, since the track jump has been performed with the number of tracks to the objective block as it is, considerable time is required to amend the track jump so that it is within 1 track before the objective block. Accordingly, the number of times of track jumping increases by 1 or 2 until the access is completed. This causes the problem of "a prolongation of access time."
For instance, with compact discs, the linear velocity of the track is different, such as 1.2 to 1.4 m/s, according to the disc. Accordingly, up to the present, errors occurred in the number of tracks to the objective block calculated as a constant linear velocity (e.g., 1.3 m/s). As a result of this error, the increase in the number of times of track jumping was unavoidable and the access time to the objective track was prolonged.
This invention is performed in view of the above conventional problem points, and its objective is to provide a track access method of discs which is able to access the track of the objective block at a high velocity by decreasing the number of track jumping times.